The subject invention relates to an apparatus and method for printing images. More particularly, it relates to an apparatus and method for printing images such as postal indicia printed by postage meters to evidence that appropriate postage has been paid on a mail piece as evidence that postage has been paid, i.e. that the prepaid amount stored in the meter has been properly decremented, a postal indicia on a mail piece.
A typical indicia includes fixed elements such as city name, state, meter identification, arbitrary and complex elements to inhibit counterfeiting of the indicia, and variable elements such as date, and, of course, a postage amount represented by the indicia. Typically indicia have been printed by complex mechanical rotary or flat bed printing elements which include a fixed printing element for printing fixed information and adjustable elements for printing variable information.
One problem with such postage meters has been providing indicia for packages or other bulky articles on which a postage meter cannot print directly. Heretofore indicia for packages have been printed on separate labels or tapes which were then applied to the package in the same manner as a postage stamp. While generally satisfactory the cost of label stock represents a significant cost for mailers, particularly in developing countries where postal rates are low.
Recently postage meters using digital printing have been proposed to allow incorporation of encrypted information in indicia to deter counterfeiting as well as to simplify printing of variable information in indicia. One particularly desirable form of digital printing which has been proposed for use in a postage meter is ink jet printing, and particularly piezoelectric ink jet printing. One such postage meter is described in commonly assigned, co-pending U.S. patent application Ser. No. 554,179, filed Nov. 6, 1995, for MAIL HANDLING APPARATUS AND PROCESS FOR PRINTING AN INDICIA COLUMN-BY-COLUMN IN REAL TIME, by Arsenault et al. (E-394) In this meter a printhead having a number of ink jets is oriented transversely to the printing direction and is moved over the mailpiece to print the indicia. Because the printhead has a density of 80 jets per inch while a vertical resolution of 240 dots per inch is desired for the indicia, the printer described in the above reference application prints the indicia in 3 interleaved passes.
Thus, it is a object of the subject invention provide an improved apparatus and method for printing images such as postal indicia on packages or other bulky articles on which a postage meter cannot print directly.